Driven by a desire to find new structural polysaccharides using enzymatic syntheses or genetic engineering of microorganisms or plant hosts, researchers have discovered polysaccharides that are biodegradable, and that can be made economically from renewable resource-based feedstocks. One such polysaccharide is poly alpha-1,3-glucan, a glucan polymer characterized by having alpha-1,3-glycosidic linkages. This polymer has been isolated by contacting an aqueous solution of sucrose with a glucosyltransferase enzyme isolated from Streptococcus salivarius (Simpson et al., Microbiology 141:1451-1460, 1995).
U.S. Pat. No. 7,000,000 disclosed the preparation of a polysaccharide fiber comprising hexose units, wherein at least 50% of the hexose units within the polymer were linked via alpha-1,3-glycosidic linkages using an S. salivarius gtfJ enzyme. This enzyme utilizes sucrose as a substrate in a polymerization reaction producing poly alpha-1,3-glucan and fructose as end-products (Simpson et al., 1995). The disclosed polymer formed a liquid crystalline solution when it was dissolved above a critical concentration in a solvent or in a mixture comprising a solvent. From this solution continuous, strong, cotton-like fibers, highly suitable for use in textiles, were spun and used.
Kiho et al. (Carb. Res. 189:273-270, 1989) disclosed the alkaline extraction and isolation of poly alpha-1,3-glucan from the fungus, Agrocybe cylindracea, which was further derivatized to sodium carboxymethylglucan (CMG). This ether derivative exhibited anti-tumor properties against sarcoma. Similarly, Zhang et al. (Intl. Publ. No. CN1283633) described the extraction of poly alpha-1,3-glucan from the medicinal fungus, Ganoderma lucidum, and its derivatization to CMG.